A pregnant mouse is exposed to high levels of a chemical. Many of the mice in her litter are deformed, but when they are interbr
ed with each other, all their offspring are normal. Which two of the following statements could explain these results? a) In the deformed mice, somatic cells but not germ cells were mutated. b) The original mouse’s germ cells were mutated. c) In the deformed mice, germ cells but not somatic cells were mutated. d) The toxic chemical affects development but is not mutagenic.
The correct answers are- a) In the deformed mice, somatic cells but not germ cells were mutated and d) The toxic chemical affects development but is not mutagenic.
Mutation in the somatic cells do not pass in the offsprings and the only mutation in the germ cells can pass to the offspring because offspring are produced by the fertilization between different germ cells. Somatic cell mutation can only cause deformation in individuals but their offspring will be like normal offsprings.
The other cause may be that the toxic chemical used don't cause any mutation but just affect the development of mice so in this case genetic material will remain in normal state in deformed mouse and they will able to produce normal offsprings. So the right answer is a and d.
Spindle fibers form a protein structure that divides the genetic material in a cell. [...] At the beginning of nuclear division, two wheel-shaped protein structures called centrioles position themselves at opposite ends of the cell forming cell poles. Long protein fibers called microtubules extend from the centrioles in all possible directions, forming what is called a spindle. Some of the microtubules attach the poles to the chromosomes by connecting to protein complexes called kinetochores. Kinetochores are protein formations that develop on each chromosome around the centromere, which is a region located near the middle of a chromosome. Other microtubules bind to the chromosome arms or extend to the opposite end of the cell. During the cell division phase called metaphase, the microtubules pull the chromosomes back and forth until they align in a plane along the equator of the cell, which is called the equatorial plane. I am in AP Bio Soo xD